Use super to get much-needed MRO magic in constructor. (#1169229)

Resolves: rhbz#1169229

super does some magic along the lines of running superclass constructors
breadth-first, which is necessary for container devices that inherit first
from a non-container class.

(cherry picked from commit 2a41c32e0a7d82db993e776966268f4ab4af408a)